4# xinshou0011
Rf减少你的损失才能减少。建议你看原版书，这里译本似乎少了一句话。

看过 john hull 书的朋友来帮帮忙啊

半年前的贴了呀~~刚看到~~不知道楼主是否已经解决问题~~先发上来看看吧~~
这是原版的相应段落"To understand the reason why the second difference reduces the forward rate, suppose that the payoff of Rm-Rf is at time T2 instead of T1(as it is for a regular FRA). If Rm is high, the payoff is positive. Because rates are high, the cost to you of having the payoff that you receive at time T2 rather than time T1 is relatively high.If Rm is low, the payoff is negative. Because rates are low, the benefit to you of having the payoff you make at time T2 rather than time T1 is relative low.Overall you would rather have the payoff ar time T1. If it is at time T2 rather than T1, you must be compensated by a reduction in Rf."所以，但市场利率高时，即Rm高的时候（Rm-Rf>0），在T1获得的话就可以选择以市场利率在市场上投资从而获得高的收益，所以相对来说如果在T2获得的话，持有成本就高。（这是从持有角度看）。如果Rm低的话（Rm-Rf<0），在支付时就可以以市场较低的利率进行支付，所以相对来说如果在T2进行支付的话，它自身的收益就低了，因为付出成本高了（这是从要支付的角度看的）。所以在T1结算比在T2结算就会有优势，因而在T1时就要求更高的利率。所以作为补偿，应该减少远期利率的值。

最近也在学这本书，看了下大家的回复，是不是可以用这样的式子表示：